In the field of thermal printing and the use of heat-sensitive, coated paper or like record material in the printing operation, the coating formulation or the formulation of the substrate itself includes dyes or dye solutions which affect the quality of print and usefulness of the paper. As is well-known in the impact printing art, the carbonless paper, which is useful for transferring ink material to one or more additional sheets, is generally coated with microscopic capsules containing at least one of the reactive ingredients which reacts with another material to produce the mark that is initiated by an impact element against the paper and which impact element causes eruption of the capsules and release of the ink material.
In a typical and well-known arrangement, a top or first sheet of a manifold of sheets may include a coating on the back surface thereof and such sheet is referred to as a "CB" sheet, one or more intermediate sheets may include a coating on the front surface and a coating on the back surface and which are termed "CFB" sheets, and the bottom or last sheet has a coating on the front surface and is referred to as a "CF" sheet. The direct impact on the top or CB sheet causes a mark thereon to be transferred by rupturing the capsules on the back thereof, the CFB sheet causes formation of the mark by reaction with the coating on the front and transfer of such mark through rupture of the capsules on the back of the intermediate sheet, and the CF sheet is marked by reaction with the coating on the front thereof in a manner to provide the mark on all sheets. The color forming or precursor ingredient of the CB capsules reacts with the color developing ingredient of the CF coating to produce the mark or image.
It is in the area of the encapsulated dye solution or the internal phase liquid which has been and is being worked and developed to provide improved marking or printing on the record media. Prior knowledge of the make-up or composition of the dye solution or liquid indicates that monoisopropyl biphenyl (MIPB) is used as a dye solvent in "Trans/Rite" paper as manufactured by The Mead Corporation of Dayton, Ohio. Also, it is noted that "Santosol" is produced by Monsanto Company, St. Louis, Mo., and is acceptable as a solvent ingredient for use in the manufacture of carbonless paper. Further, it is known that Appleton Papers, Inc., Appleton, Wis., has included crystal violet lactone (CVL) blue dye and indolyl red (IR) dye to make a solution for blue printing, and that N-102 dye has been used in a formulation to provide an improved resistance to CB decline, which is the reduction in ability to produce a satisfactory image after accelerated light exposure.
Representative documentation in the field of carbonless paper relative to the subject matter of the present invention includes U.S. Pat. No. 2,850,395, issued to B. K. Green on Sept. 2, 1958, which discloses a printing fluid containing a red dye and a preferred color reactant such as crystal violet lactone.
U.S. Pat. No. 3,525,630, issued to P. S. Phillips on Aug. 25, 1970, discloses a colorless ink to give a black print, the composition of the ink including an organic oil solution of crystal violet lactone, benzoyl leuco methylene blue, and a phthalide structure.
U.S. Pat. No. 3,681,390, issued to C. H. Lin on Aug. 1, 1972, discloses a chromogenic compound consisting of at least a dialkylamino fluoran of substantially colorless texture and reactive with a color developing or activating material to yield dark-colored substances.
U.S. Pat. No. 3,940,275, issued to B. W. Brockett et al. on Feb. 24, 1976, discloses record material and a colorless but colorable marking liquid composition of an organic oil solution of a colorless reactant comprising dimethylaminophthalide (CVL), phenothiazine, and methylfluoran in amounts to yield an apparent blue-colored mark.
U.S. Pat. No. 3,981,735, issued to M. Murata et al. on Sept. 21, 1976, discloses a colorless liquid ink composition comprising an organic peroxide compound dissolved in water insoluble organic oil and a color reactive dye material.
U.S. Pat. No. 4,001,140, issued to P. L. Foris et al. on Jan. 4, 1977, discloses capsule manufacture with an oily solution of colorable dye materials including crystal violet lactone (CVL) and indolyl red (IR) in a mixture of solvents for producing blue and black print.
U.S. Pat. No. 4,012,554, issued to R. E. Miller et al. on Mar. 15, 1977, discloses a colorless liquid ink or internal phase liquid for use in microcapsules, the composition being a solvent vehicle having colorless chromogenic material (CVL), color-developing reactant material (phenol), and the colored dye resulting from reaction between the chromogenic material and the reactant material.
And, U.S. Pat. No. 4,275,905, issued to R. E. Miller on June 30, 1981, discloses a substantially colorless marking liquid comprising a colorless chromogenic material (CVL), a solvent for the chromogenic material, and an additive such as Pyridyl Blue (PB) and a phenol for controlling CB decline.